Marine pollution due to hydrocarbons, especially petroleum products has been analyzed in detail with respect to the amount of petroleum introduced due to accidents, the direction of petroleum flow, the state of dispersion thereof, decomposition and scattering effects due to flowing petroleum on the sea, shoreline pollution and the like.
Further, microbial decomposition oil has also been reported. For example, one theory postulates that in the case of petroleum spread on the surface of the sea as a "membrane" 0.1-0.4.mu. thick, components which do not volatilize are attacked by various microbes within 1-2 weeks so that a considerable part of the petroleum is decomposed within 2-3 months. Further, it has been reported that the amount of decomposition due to other organisms or due to spontaneous oxidation is about 1/10 that due to microbes.
At present, there is a rapid growth of knowledge concerning petroleum and its effects on the marine environment and organisms having a relationship therewith one detailed report is "Collective investigation for environmental influence concerning matter of oil flowing in Mizushima" issued by the Environment Agency of Japan on March 12, 1977. Per this report, oil introduced into the sea seems to be substantially decomposed or dispersed after 1 year. However, per oil pollution investigations by the International Oceanography Committee (IOC) of the United Nations Educational, Scientific, and Cultural Organization (UNESCO) and the World Meteorological Organization (WMO) during 1975-1979, it appears that marine oil pollution results in serious problems which cannot be reconciled with the theory that almost all oils are assimilated by microbes without the passage of long periods of time. In fact, it was recently reported that many oil tankers had serious problems arising from washing the holds of supertankers and throwing sludges away and others relating to oil tankers, which created an abrupt realization of this type of problem with those concerned with marine pollution and, led to a discussion of such problems by governmental bodies. Further, the fact that treatment of oils having a low concentration drifted near to shore is very difficult to carry out has become an issue.
The act is aware of processes for separating petroleum decomposing microbes or petroleum component decomposing microbes such can roughly be classified into two methods. One uses a culture medium composed of inorganic marine salts, NH.sub.3 salts (or urea) and petroleum or petroleum components; the other uses a culture medium prepared by adding an eutrophic material such as a vitamin, Casamino acid or a yeast extract to the above described culture medium. It is known that in the case of multiplying oxidative microbes complex having activity in a high nutrition condition such as in the latter method the culture medium becomes cloudy by shaking cultivation at 20.degree. C. for 10 days.